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參數(shù)資料
| 型號(hào)： | TFS225A |
| 廠商： | VECTRON INTERNATIONAL |
| 元件分類： | 聲表面波濾波器 |
| 英文描述： | VI SAW濾波器(VI SAW Filter) |
| 中文描述： | SAW FILTER |
| 文件頁(yè)數(shù)： | 2/3頁(yè) |
| 文件大小： | 21K |
| 代理商： | TFS225A |
Ltp: tft031
______________________________________________________________________________________________________
VI TELEFILTER
Application Note
______________________________________________________________________________________________________
3. Matching on the PCB
8
LB-IN
version 1.0
29.09.2000
TFS 225 A
2/2
VI TELEFILTER
Potsdamer Strae 18
D 14 513 TELTOW / Germany
Tel: (+49) 3328 4784-0 / Fax: (+49) 3328 4784-30
E-Mail: tft@telefilter.com
VI TELEFILTER reserves the right to make changes to the product(s) and/or information contained herein without notice. No liability is
assumed as a result of their use or application. No rights under any patent accompany the sale of any such product(s) or information.
Vectron International, Inc.
267 Lowell Road
Hudson, NH 03051 / USA
Tel: (603) 598-0070 Fax: (603) 598-0075
E-Mail: vti@vtinh.com
2
1
7
3,5,6,9,10,11,12
LB-OUT
SAW
C1
L1
C2
L4
L2
L5
L3
4
L1 = L2 = L3 = L4 = 56 nH
C1 = 0,7 pF
C2 = 0,5 pF
L5 = 150 nH
The matching on the PCB does slightly differ from the theoretical matching. The reason for
that are parasitics of the PCB and of the transformers.
But if the parasitics on the customer board (mentioned parasitics, additional parasitics of
active parts) are different to this PCB the matching elements have to be slightly adjusted. Both
in line and shunt elements change both passband tilt and passband ripple. But
- the in line coils mainly influences the pass band ripple
an increase of the inductivity of the in line coils will decrease passband ripple or change a
flat pass band shape towards a round one
- the shunt capacitors mainly influences the pass band tilt
an increase of the capacity value will change the tilt to lower attenuation on the low
frequency side of the passband
The coupling coil mainly influences the bandwidth in passband of the filter
The strategy to match the filter on the customers board should be as follows:
-
match the filter according to theoretical values to 50 Ohm.
Use your final PCB for this matching to be sure to have the stray elements of the PCB then
before.
-
Adjust external coil according to stray elements of the PCB
The external coil influences the bandwidth of the filter by influencing the upper transition
band of the filter only. The position of the lower transition band is not influenced. That
means a wrong value for the external coil will lead to wrong bandwidth and wrong centre
frequency. The group delay of the filter is influenced in the same way. There are two peaks
in group delay behaviour for the matched filter. The peaks in group delay are located at the
pass band edges of the filter. Finally this means that only the higher frequency peak in
group delay is influenced by the external coil. This makes the adjustment of this coil very
easy. Make sure that the distance in frequency of the two group delay peaks is identical
with the distance shown in the delivered plots. (around 340 kHz) The matching of the
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| TFS225E | 制造商:VECTRON 制造商全稱:Vectron International, Inc 功能描述:Filter specification |
| TFS228 | 制造商:VECTRON 制造商全稱:Vectron International, Inc 功能描述:Filter specification |
| TFS230 | 制造商:VECTRON 制造商全稱:Vectron International, Inc 功能描述:Filter specification |
| TFS230_05 | 制造商:VECTRON 制造商全稱:Vectron International, Inc 功能描述:Filter specification |
| TFS235A | 制造商:VECTRON 制造商全稱:Vectron International, Inc 功能描述:Filter Specification |
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